Method of and mold for casting wheels



(No Model.)

E W. G. RICHARDS.

METHOD OF AND MOLD FOR CASTING WHEELS.

No.-451,901. Patented May 5,1891.

mm; 06 In venzor I Will 6.131217: fiyhiddm gi r J 6 M FFICE.

\VILLIAM G. RICHARDS, OF BOSTON, MASSACHUSETTS.

METHOD OF AND MOLD FOR CASTING WHEELS.

SPECIFICATION forming part of Letters Patent No. 451,901, dated May 5, 1891.

Application filed October 25, 1890., Serial No. 369,297. (No model.)

Too/ll whont it may concern:

Beitknown that 1, WILLIAM G. RICHARDS, a citizen of the United States, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in the Art of Making Castings, of which the following is a specification.

This invention relates to the art of making steel castings in molds, the object being to furnish a method or process whereby the metal first entering the runner is detained outside of the mold and whereby the moldfilling passages may be reduced to a thickness within the normal non-piping limit.

In the drawings accompanying and forming a part of this specification, Figure 1 is a vertical section through the mold and illustrates the beginning of the process. a similar view showing the mold after the same has been filled. Fig. 3 is a diagrammatic view similar to a portion of Fig. 2 and illustrates the action of the elastic abutment. Fig. 4 is another diagrammatic view illustrating certain features of the process. Fig. 5 is a diagrammatic View illustrating the closing stage of the mold-filling operation.

Similar characters designate like parts in all the figures.

The mold shown in the drawings is or may, in its general features, be the same described and claimed in my prior application, Serial No. 358,657, filed July 14, 1890.

By the term piping as applied to the piping of steel castings I do not refer to the small pin-holes and cavities sometimes found throughout the mass of the casting, but refer instead to those elongated openings naturally formed in the interior of the casting after the outer surface of the casting has solidified and by reason of the joint action of contraction and the attraction of cohesion, whereby metal in the interior and most fluid part of the mass as congelation sets in is drawn outward to supply the shrinkage just within the aforesaid surface of the casting.

The flask for containing the mold proper consists or may consist of the bottom board 52, the nowel-frame S, the chill 10, and the cope-frame 9, all substantially as set forth in my prior application, Serial No. 358,655, filed July 14, 1890. The mold proper consists of Fig. 2 is substantially as indicated in the drawings.

The pouring-head, designated in a general way by C, is attached to one side of the mold at or near the base thereof and extends to a point at some elevation above the top of the mold, substantially as indicated in Fig. 1. The parts forming the top and side walls of the mold-space maybe changed or modified, as circumstances may require, these parts not being peculiar to my present invention. The main runner 12, through which the metal is conducted to a point adjacent to the under side of the mold, is formed in the nowel immediately under the mold-surface, and is supplied by the channel 12 of the pouring-head, which extends downward and connects with said horizontal runner, substantially as indicated in Figs. 1 and 2. p

The main runner 12 communicates with the mold-space through one or more mold-filling passages, as 13, which branch off from the main runner at a point some distance before the termination ofsaid main runner. Said mold-filling passage or passages are of relatively small cross-sectional area and should be of a thickness not greater than the described non-piping limit.

In the cope of the mold are formed a series of vents or overflow-passages, those over the hub-space being designated by 32, while those over the rim-space r of the mold are designated by 30. The usual arch-core 50 is provided to form the space between the upper and lower plates of the wheel when the mold is made for casting a double-plate wheel; also, the usual center core 52. is or may be provided for making the central opening in the hub of the wheel-casting. The arch-core divides that part of the mold-space surrounding the hub-space into the front-plate space 6 and the back-plate space 5, as indicated in the drawings. That part of the mold surrounding the arch-core between the rim-space and said arch-core is designated as the single-plate space 7 K The horizontal runner 12 is extended beyond the vertical passage or passages 13 to form a catch-chamber 20, constituting a receptacle for the first inflowing metal and to catch the debris and wash of the pouringhead surfaces always accon'ipanying the first influx of metal; also, to hold at a high temperature during the last stages of the process a quantity of metal, serving as a heat-reservoir for prolonging during the last part of the pouring operation the fluidity of the metal in the said connecting passage or passages leading to the wheel casting. The wheel-casting shown in section in the mold in Fig. 2 is a car-wheel of the double-plate variety, having the rim R, the hub 41, the back plate 5, the front plate 6, and the single plate 7, which single plate may be considered as a continuation of the two plates 5 and G for joining these two plates with the rim.

In the operation of pouring the mold the highly-heated molten steel is poured into the pouring-head C and follows down through the large runner 12 in a full stream and at a rapid velocity, due to the height of the pouring-head, and flows along the horizontal part of the main runner until it strikes abruptly against the abutment formed at the terminus of said large runner. During this passage and at the first touch of thehot metal against the cooled surfaces of the mold there is formed a thin coating or scale adhering to the granular material of the mold and constituting a heated metallic tube, within which the molten steel afterward continues to flow during the pouring operation. At the moldfilling passage or passages 13 said metallic tube or casing (there being a space at said passages rather than a continuous surface) is formed thinner or with a break therein. On the metal striking the abutment beyond said passages there occurs a violent reaction in the nature of a blow, whereby the metal'in the large runner contiguous to said passages is forcibly impacted between the metal against the abutment and the oncoming heavy stream from the pouring-head. The effect of this reaction is to imparta sudden and violentpressure to the metal immediately at the said moldfilling passages, whereby the aforesaid scale or tube (when the same has formed at said passages) is burst through, and whereby the metal then in the large runner at said passages is violently driven at a high velocity through the passages into the mold. Bythis method of inaugurating the mold-filling current or stream of metal (by which term I designate the current in the aforesaid passages 13) the highest attainable velocity of said mold-filling currents is obtained, whereby the cross-sectional area of said passages may be reduced to a minimum. By this method of casting, the first metal entering the runner suffers the greatest chilling of any metal entering the mold during the pouring operation, since it traverses the entire length of the large runner, and thus comes directly in contact with thelargest area of cold in old-surface. By reason of the cooling of the firstinflowing metal this first metal becomes unfit for or incapable of entering the mold through a sufficiently small mold-filling passage, and

hence, according to my present invention, said cooled first inflowing metal is carried beyond said inlet-passages and is detained from entering the mold, being utilized for effecting the impact above described by which the moldfillingcurrentis inaugurated. Afterthepouring operation is begun and said mold-filling current or currents are established the cooled metal first'delivered into the large runner beyond said mold-filling currents is gradually reheated, so that at the end of the pouring operation it becomes substantially uniform in temperature with other parts of the runner, this reheating taking place gradually by reason of and from the action of the currents existing in said runner and passageways. At the moment the first inflowing metal reaches the terminus of the large runner the elongated mass acquires a considerable momentum, and thus acts on the principle of a ram to drive the metal laterally through the small runners with a relatively great force. This feature will be readily understood when it is observed that the aggregate mass of the heavy fluid metal in the large runner is very considerable, and the velocity, owing to the height of the head 0, is also considerable, thus furnishing ample means for causing a reactionary effect of high intensity. WVhere two or more of the small secondary passages 13 are used, the one nearest the terminus of the large runner will first receive the effect of the reaction described above, which will be quickly extended to the runner or runners more distant from the abutment. The movement of the large stream of metal being more sluggish than is desirable for the stream entering the mold, the metal in the large runner is carried beyond the mold-filling passage 13 against an abutment which operates by reaction to break the column at said mold-filling passage and drive the metal at said point in directions which are resultants of the forces of action and reaction. This is indicated in the diagrammatic Fig. at, where the arrow at indicates the direction of the oncoming stream of metal, and of course of the momentum of said stream, while the arrow 1) indicates the direction of the resistance caused by the aforesaid abutment. These two forces coact to drive the metal laterally, as indicated by the arrows c and d at the point of least resistance, which point occurs at the intersection of the branch runner 13, as shown. It the walls of the chamber 20 immediately before the abutment 22 be sufficiently vented, the air contained in said chamber orpocket will escape before the oncomihg current of metal and the metal be driven or impacted directly against said abutment, as indicated in Fig. 2, so that the reaction will be sudden and correspondingly intense; but in practice not only is it desirable to secure the described reaction, but also to prolong the reactionary effect until the resulting mold-filling current is thoroughly established at a high velocity. This object is secured by making said chamber or pocket only slightly vented or pervious, so that on the approach toward the abutment of the large stream of metal some air (or mingled air and gases) is temporarily caged or shut in the chamber to serve as an elastic or cushioned abutment, forming a spring whose effect is to prolong the reactionary effect by driving back somewhat the body of metal in the chamber, thus supplying the mold-filling current or stream from both sides of the small runner 13, as indicated by the curved arrows at c, Fig. 3. This operat10n being in point of time very quickly carried out, there is then no further use for the air constituting said cushioned abutment, and said air is gradually exhausted through the pervious walls of the mold or through a small vent, as 24, Fig. 3. By means of this process of filling the mold it is made practicable to use a mold having the inlet-passages of less thickness than the non-piping limit without causing congelation of the steel within those passages before the mold-filling current is fully established therein.

For an explanation of the special utility of using mold-filling runners of a size less than the normal non-piping dimension, it is necessary, as I understand it, to take into consideration the peculiar behavior of steel in the operation of casting as modified by the necessary feeding of the mold after the same is first filled. It is well understood that steel when cast has at a certain moment in the cooling thereof a sudden and relatively great shrinkage, which it is supposed takes place at about the point of temperature where congelation sets in. The result of this sudden action must necessarily be either to pipe the casting or to draw together the outer shell thereof, it being understood that some moments before general congelation sets in a comparatively strong shell is formed by cooling over the surface of the casting, excepting at the point where the casting is being fed, this point being still molten by reason of the continued inflow of hot metal through the mold-filling runners. The piping effect or tendency is strongest, as is well known, at the interior of the mass, so that by reason of the gradual cooling from the outside toward the interior the most effective feeding of the casting can be attained only by the highest velocity practically attainable of the feedingcurrent, this being a prolongation (in point of time) of the mold-filling current through the outer part of the casting into said inte rior. If now the runner joining the casting be of relatively large size, the velocity of the feeding current is reduced, and there is formed therein a tendency to pipe on cooling, the piping of the runner following into the casting and joining the piping in the interior thereof. This results in forming a defect or break in the continuity of the surface of the casting, thus weakening the whole structure, besides directly antagonizing the solidifying of the interior of the casting by reason of a counter-suction produced by the internal shrinkage and consequent suction within the runner itself. By reducing the runners below the non-piping limit the congelation, when 7 it finally extends to the runner, seals over and closes the outer part or shell of the casting at the point where the runner enters the same, thus forming an unbroken and perfect surface for the casting and so closing the exterior shell of casting that the internal shrinkage and suction have the effect of drawing together the shell for closing the interior pipe, which otherwise would naturally form in the interior of the casting; but, as above pointed out, runners small enough to produce the peculiar effect required are impracticable for use unless means be had for successfully inaugurating the mold-filling current, which according to my present improvements is attained, as hereinbefore explained, by means of a reactionary effect, whereby the metal first entering the runner is not delivered into the mold, but is utilized for other purposes, and whereby the mold is first filled by metal following the first inflowing metal. This fea ture is illustrated in Fig. 5, wherein the lightshaded part 60 designates the region of fluid metal at the moment before closure by congelation of the feed-passage at 13.

After the mold is completely filled and the exterior of the casting is solidified, as indicated by the dark shade at 61, Fig. 5, congelation gradually extends toward the interior of the casting, and also gradually extends inwardly throughout the main runner and through the mold-filling runner, the contraction due to congelation being supplied by the current through the vertical runner 13, as indicated by the light-shaded passage at 62 in the drawings. As the congelation extends close to the center of the casting, leavingbut a small part, as 60, remaining fluid, the contraction of the metal becomes more rapid, producing a suction increasing the speed of the feed-current 62, which operates, by reason of its considerable velocity, to keep open the passage 13 through the lower surface of the casting and to delay the closure thereof until the latest possible moment. The feedcurrent 62, being thus accelerated, is maintained, as described, until it becomes relatively very small and is reduced to a size less than the normal size of a globule of congealing steel, so that 011 the final closure or 0011- gelation of the metal at 13 no pipe can form, but the surface is closedby cohesion and left perfectly sound. After this, final shrinkage of the metal in the hub of the wheel goes on gradually and normally until the metal is cooled in a solid form.

In the double-plate style of Wheel shown in the drawings there is normally in the hub two piping-lines, one at the juncture of the upper plate and hub and the other at the juncture of the lower plate and the hub. The upper pipe is naturally and readily filled by the upflow of hot metal in the interior of the hub,

and for the reason that the upper plate 6 of thewheel cools most quickly, owing to the rapid radiation of heat from the upper side of the mold, While the lower plate remains molten. The lower pipe is filled, as above described, by a small accelerated current from the main runner, which is kept supplied from the pouring-head.

The small or mold-filling passage or runner is set vertical to the normal piping-line ot the hub, so that the forced stream of metal is delivered directly to the point of greatest suction, as best shown in Fig. 5.

Having thus described my invention, I claim-- 1. That improvement in the art of making steel castings which consists in running the metal through a main runner adjacent to the mold-space and against an aircushioned abutment, flowing the metal from the main haust the air during the pouring of the mold. 35

WILLIAM G. RICHARDS. \Vitnesses:

FRANCIS I-I. RICHARDS, HENRY L. RECKARD. 

